In the manufacture of multi-layered elements, in particular of elements of III-V compounds like gallium arsenide, liquid-phase epitaxy becomes more and more employed. In contrast to elements on which semiconductor layers are deposited from the vapor-phase, life expectancy as well as efficiency are notably improved. For liquid-phase epitaxy, the surface of a substrate is brought into contact for a defined time with an oversaturated solution whereby a specific epitactic layer grows on the surface. In subsequent process steps, the same surface is brought into contact with another oversaturated solution in order to grow another epitactic layer. The process may be repeated many times. There is a trend in industry to ever thinner epitactic layers with ever-growing quality requirements. Thus, as the contact times between solution and surface decrease, the requirements as to purity of solutions, cleanliness of vessels, etc. increases. Also, it is necessary to remove one solution completely before the subsequent solution comes into contact with the surface. Finally, it is desirable to recover the solutions for further use, without contamination. Several implements and devices are already known in the art for the execution of multi-layered liquid-phase epitaxy. A first group of devices works with sliders which move between different chambers of a crucible which contain different solutions. U.S. Pat. No. 3,565,702 shows one embodiment. Another embodiment, with circular crucible and a circular slider, is shown in U.S. Pat. No. 3,881,037. For certain applications, these systems have the drawback of relatively complicated structure, of requiring high precision machined parts and of moving, with the substrate, an amount of a solution which then mixes with another solution. Also, the time of contact between substrate and solutions cannot be made sufficiently short. Also, as a result of abrasion of crucible parts, which slide upon each other, the solutions can become contaminated and the substrates, in particular epitactic layers, may be damaged by mechanical influences.
In another group of systems, the exchange of solutions on the semiconductor substrate is done by rocking. An example of this group is shown in IBM Technical Disclosure Bulletin, volume 14, No. 9, page 2850. Although this apparatus shows little admixture of solution residues with the subsequent solution, the contact time, however, is too long for many applications.
A third class of devices is provided with rotating crucibles in which the transport of liquids is by means of gravity. One example is shown in U.S. Pat. No. 3,858,553, another one in IBM Technical Disclosure Bulletin, volume 18, No. 5, page 1585. The crucibles rotate slowly and contact times between substrates and solutions are long. In more recent designs, there is a trend to shorten the contact time by employing centrifugal forces besides the force of gravity. The paper by Bauser, Schmid, Lochner and Rabe, in Japanese Journal of Applied Physics, volume 16, 1977, supplement 16/1, pages 457 through 460, as well as literature cited there, describe examples of such devices. The crucible by Bauser et al. allows short contact times between various solutions and semiconductor substrates. Furthermore, the solutions are recovered for further use without essential mutual mixture. A disadvantage can be seen in that the crucible consists of many parts, which need precise machining. During operation, the parts within the crucible slide upon each other, thus giving cause to contamination of the liquids. Finally, under the influence of centrifugal force, the solutions repeatedly are forced to flow through narrow gaps which would stop normal flow due to surface tension of the solution. Therefore, solutions of high surface tension cannot be used.